"We don't know who was in command of the invasion force but the feeling is he should brush-up on his map reading.

"But to be fair he was only a couple of hundred yards from the right spot."

Spain and Britain are Nato allies but are locked in a long-running dispute about the sovereignty of Gibraltar.

Spain magnanimously spared Britain's blushes by accepting the landing had been a genuine mistake.

The marines were sailing on HMS Ocean

"We are not going to protest. From our point of view the
matter is closed," a Foreign Ministry spokesman said.

The British Ministry of Defence said it was a situation it would "rather not have taken place".

"Two landing craft from HMS Ocean accidentally entered
Spanish territorial waters and in bad weather one landing craft
landed on the beach a few yards over the Spanish side of the
border," a spokesman explained.

"About 20 Royal Marines disembarked for about five minutes
and then the error was recognised and they all withdrew."

The gaffe came at an unfortunate time as talks between Foreign Secretary Jack Straw and his Spanish counterpart, Josep Pique, aimed at ending the centuries old dispute over the rock have stirred up animosity in both countries.

Gibraltarians and their political leaders are furious at suggestions that sovereignty of the peninsula could be shared.